Frictional servomotor



June 21, 1949. s. J. MIK'INA 2,473,896

FRIcTIoNAL sERvoMoToR Filed Nov. 28, 1947 3 sneaks-sheet 5 wlTNEssEs; I INVENTOR an/eyJM/K/na. BY 6... u-

` g3) ATTORNEY Patented `lune 21, 1949 FRICTIONAL SERVOMOTOR Stanley J. Mikina, Pittsburgh, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 28, 1947, Serial No. 788,346

Claims. (Cl. 139-142) My invention relates to frictional mechanisms which transform rotary motion into translational motion of controllable velocity, acceleration, or extent of travel for positioning, regulating and the like control purposes or for the purpose ci power transmission or propulsion. Such mechanisms are disclosed in the copending patent application Serial No. 788,866, led November 29, 1947, and also in my Patent No. 2,428,807, both assigned to the assignee of the present invention.

The main objects of my present invention are to simplify such mechanisms and to make them more rugged and more reliable.

In mechanisms of the type here dealt with, an elongated driven rotor is frictionally engaged by a friction roller which is mounted on a movable carrier to impart translational movement to the carrier when the roller axis is turned out of parallelism with the axis or generatrix of the rotor, and a control device serves to move the roller axis bach to parallel position as the carriage advances along its path of travel. In the designs of the mechanism disclosed in the abovementioned patent, the control device for turning the axis ci the friction roller includes a gear rack which extends along the path of carriage travel and is engaged by a pinion journaled -in the carriage. The control device of this gear type, if designed to operate with desired smoothness, is relatively intricate and is inherently limited as regards the law of dependency of the roller return adjustment upon the travel of the carriage.

It is, therefore, also an object of the present invention to eliminate geared control devices of the rack-and-pinion type, and it is further aimed at devising a control that permits more latitude as regards the law of roller return adjustment.

Still another object of the invention is to provide a irictional mechanism of the type mentioned whose driven structure is composed of a lesser number of parts and of considerably reduced weight or mass than in the mechanisms heretofore disclosed so as to permit a corresponding increase in acceleration and deceleration.

Another object of the invention is to devise such frictional mechanisms in a manner that readily permits adjusting the frictional engagement between driving rotor and friction roller with the aid of stationary adjusting means accessible from the outside and without requiring a disassembly or a removal of the friction roller carriage.

cordance with my invention, I provide the pivot shaft of the friction roller with a crank member which is engaged and controlled by an elongated cam member whose cam surface extends along the path of travel of the driven carriage. According to another feature of the invention, the cam member consists essentially of a slotted lever whose movement initiates the carriage travel. These and other features will be apparent from the following description of the embodiment shown in the drawing.

The illustrated servo-mechanism is designed as a drive for the ily shuttle of a weaving loom. Figure l shows a part-sectional view in the axial direction of the driving rotor, Fig. 2 a View taken from the right-hand side of Fig. 1, and Fig. 3 a top view relative to Fig. 1. Fig. 4 is a sectional view of carriage and friction roller, and Fig. 5 shows, partly in section, the slotted lcontrol lever and appertaining control devices of the shuttle drive.

In the drawings, numeral I denotes a composite stationary frame or supporting structure. A rotor 2 of elongated cylindrical shape is revolvably mounted in bearing plates 3 of the frame structure. The shaft 4 of rotor 2 is connected to an electric drive motor (not shown) operating substantially at constant speed. The rotor 2 is maintained in continuous revolution during the operating period of the Weaving loom. Held against the cylindrical surface of the rotor is a friction roller `5. Roller 5 is mounted on a ball bearing 6 whose hub portion is seated on a hollow shaft 1 (Fig. 4). As shown, the roller 5 consists of the outer race member of the ball bearing which has a normal design, except that its outer surface is ground to a slight curvature to reduce the starting torque required to tilt the roller. The roller shaft I is attached to a fork-shaped supporting member 8. Integral with this member is a pivot shaft 9. The axis of pivot shaft 9 extends at a right angle to the geometrical axis of rotor member 2. The axis of revolution of the roller 5, i. e. the geometrical axis of hollow shaft l, extends at a right angle to the axis of pivot shaft 9.

Shaft 9 is journaled in a thrust bearing I0. Bearing Ill rests against a carriage structure II' equipped with four ball-bearing wheels, all deo noted by I2. The wheels engage two rails I3 and In order to achieve these objects, and in accapable of permitting movement of bearing One end of each spring rests against a bra-cketgrlO 2| oi" the appertaining rotor bearing plate The other spring end abuts against anadju'stin'g- I unit seated on bolt I6 or I1. The. ma(shinedlnirigei. portion I5, as shown, is preferably locatedat-thejr,

base of a vertical line (Fig. 1) through :theqaointif 15:

of application of the spring forceontheshuttle. box 26 and the point of contact of roller 5 'with' rotor 2.

It will be recognized that the springs I6 and I1, as compared with the biasing mechanisms `dis-.5l 2O closed in the above-mentioned patent, are not disposed on the carriagelll. sothat thescarriage structure can be given a greatly simplied design, of considerably reduced weight or mas s.v As aa.

further result, the springiorce can .readily be-.25

adjusted without requiring .a .removalnor disassembly of the carriage.

Attached to the carriage structure I Iisa mem-4 ber 22 that carries a metal cup 23 for engaging.

the fly shuttle 24 to be propelled by the mechaA 3Q nism. The cup 23 also serves to bring theshuttle to a stop on its return from theotherside of the., loom. The returningshuttle is .brake'd when it enters the shuttle box20 by lwedging itself .be-

tween spring-backedfriction shoes 25, 26 (1"'ig.,1) g;

extending the lengthof the shuttle .boX.2 Il'..l Cup- 23 is filled with rawhide' or other suitableresilient l, material to be engaged by the steel-tipped nose of the shuttle.

When the axis of revolution of friction roller. 4p

5 is in the illustrated .position of parallelism 4with the generatrix of rotor 2, the.revolution of the rotor has merely -the effect of revolving-.the roller y 5 but imparts no driving force to. the carriage;l structure II. twisting the roller axis relative to the generatrix of rotor 2, the carriage assembly is propelled along the rails at a, velocity substantially equal to the peripheral velocityv of the rotor times `the tangent,y

ofthe angle through which shaft 9 has '.turne'd. 50

In order to impart high translational accelera.

tion to the carriage or shuttle, fory instance inthe order of 100 times gravity,. the angular adjustments of the shaft 9 must be accurately controlledwithin short intervals of time. For .examplain- 55..

a specific loom shuttle drive, the4 shuttle. isy uni-v formly brought up to a speed of. V15,feet persecon'd Within about /o second atr the end of inches of' travel. From this point on, the carriage begins a uniformr deceleration that bringsit. to .a

stop in another 6 inches of travel, while the shut-v tle travels under its own momentum to the,other. side of the loom. The means for securing. a c on.

trol of this kind will be described presently..

The pivot shaftV 9 carries anfarm or the like. crank member 21 whose actuating end is equipped with a roller 28 to engage. the cam surface of. a -Y cam member 29 (Figs. v1, 4,' 5) The cammember is Idesigned as an elongated leverand extends along the rotor 2 and along 4the path of travelof. J7

When shaft 9 is. turned, therebyA 45 shape. Preferably, however, the slot and cam surface are given a curvature such as illustrated in Fig, 5.

The lever 29 has two pivot pins 3| and 32 located near the respective ends of the cam slot 28. Pivot pin 3I is linked to the piston assembly 33 of a hydraulic adjusting device whosefcylinder 34 is rml-y.;attached.:to1 a par-t. 35. .appertainingwto the frame structure I. A return spring 36, extendingbetween part 35 and lever 29, tends to hold the pivot pin 3| and piston assembly 33 in the illustratedV position'. When hydraulic pressure is applied,. the.` assembly. and pivot are moved down- Ward in oltllclosition toj, spring 36. When the pres- .sure is releasedthe. pivot is returned to the illustrated normal position of rest by the biasing force of spring 36'."

The pivot pin 32 is linked to the piston assembly 31 of another hydraulic adjusting device which is. firmlyv attached to the frame structurel andequipped.'withareturn spring 39. When., hydraulic pressure is applied to cylinder 38a.

pivot 32`is lifted in oppositionto spring .39..

The fhydraulic ypressure is provided, and con-.. trolled-by a system .which .isfdesigned inaccordance `withthe principles disclosed inthe copend ing application SerialNo..'187.,230, led. November. f 20,1947 of L.' BL` Lynnand S. J.. Mikina.Y The,.- system includes a four-.way valve, denoted asa whole by 40', and a source of pressure 4I. consist-T ing of a positive displacementpump, such as; a

gear pump. The pump has an inletduct42 which.. leads into the sump iorHloW-pressure side of the.

pump, and communicates with'two conduits 43 and44 leading .to' the low-pressure sides of .theyx respective piston rassemblies 33"and 31 in therespective cylinders 34gand y38 of the two pivot adjusting devices. The outlet duct of v,the pump 4 Iisconnected by two pressure conduits 45I.an d 46,1. to respective `chambers 41`and 48fof valve .40.1 These` valve chambers are in communication with the high-pressure sides within thecylinders 34' and 38 by pressure conduits 49 and 59., 'respec..V

tively'. Two spring-'biased check valvesEI and 52" establish a communicationofY respective valve...

chambers 41 and 48"with theneutral orinlet curs within the valve chambers.

valve chamber 41. A similar double-acting valve member 54^is located 'in chamber 485 Valve members 53""and 54" "are rigidly interconnected by a rod 55'which carries'a magnetic armature lfmovable between ytwoA electromagnets -51' and. 58 and/1 normally biased bytwoy springs'59 and ,E ljto assume the illustrated centered position; TheV two magnets 51 and 58" arefconnected to a suitable... current source schematically represented at 6I," and are controlledby a switch`62 The switchhas a movable control member63which is normally I. in theillustrated open positionand can be' tilted either way tov energize magnet-51for 58. v Consequently, when the switch 62 is'actuated, only one ofthe two'magnetsl is energized at'a time and,.by

attracting the armature 56,' causes thetwo valve .-me1 nbers53 and 54*to move either to the right or to the left," depending uponwhichlmagnet is in. ,l

operation.

When'the pump`4l" is running andthe switch member 63 in the illustratedcenter positin, the

camsurface formed f therebyrmay' have linear^75`-ffour'individual valve's of whichthe members 53 and` '4'form part are all open. Consequently, a continuous ow of liquid is maintained through conduit 45, chamber 41, cavity 64, and neutral duct 42; and'a second path of continuous fluid circulation exists from conduit 46 through chame ber 48 and cavity 64 to duct 42. As a result, the pressure applied to the cylinders 34 and 38 is insuilicient to move the piston assemblies in opposition to spring 36 or 39, and the cam lever 29 remains in the illustrated position. When under these conditions the carriage |I is located at the left end of its path of travel with cam roller 28 at the place shown in Fig. 5, the axis of friction roller 5 is parallel to the generatrix of rotor 2. Consequently, the friction roller does not impart movement to the carriage I I.

When now the switch member 63 in Fig. 5 is moved to the left to energize the magnet 51, the armature 56 and the valve members 53 and 54 are shifted to the right. This has the effect of closing the communication between conduit 45 and chamber 41 or of increasing the ow impedance in that communication while more freely opening the chamber 41 toward the cavity 64. At the same time, the communication between pressure conduit 46 and chamber 48 becomes more freely open, while the communication between chamber 48 and cavity 64 is closed or more obstructed. The pressure from conduit 46 is now applied through chamber 48 and conduit 50 to the cylinder 3B with the effect of lifting the pivot pin 32. The pressure from conduit 45 is blocked from acting through chamber 41 and conduit 49 on the cylinder 34 so that the pivot pin 3| remains in the illustrated position of rest.

The resulting movement of the lever 29 is a. rotation about the then stationary pivot pin 3|. The roller 28 is lifted, relative to Fig. 5, and performs a movement which, relative to Fig. 4, extends cut of the plane of illustration, for instance toward the observer. It will be recognized from Fig. 4 that such a movement of roller 28 causes the axis of roller 5 to assume an angle relative to the generatrix of rotor 2 at the point of contact between rotor 2 and roller 5. As explained above, this results in an acceleration of the carriage II along the rails I3 and I4, the travel being in the direction fromV the left to the right relative to Figs. 2, 3 and 5.

During the travel of the carriage, the roller 28 moves along the slot 3U. The maximum speed of the carriage is reached when it is approximately at the center point of the available distance of travel. Beyond this point, the roller 28 is progressively turned back so that the carriage decelerates and is eventually brought to a stop near the right-hand end of lever 29 when the axis of roller 5 is again in parallel to the generatrix or axis of revolution of rotor 2.

During the second half of the carriage travel, the switch 63 is returned to the initial position so that the pivot pin 32 returns to the illustrated position of rest. Consequently, when the carriage reaches the end of its travel, the lever 29 has again the position shown in Fig. 5. When, thereafter, the switch member 63 is actuated in the opposite direction, the pivot 3| is lowered in order to cause the carriage to be accelerated in the return direction. When, thereafter, the switch member 63 is returned to theinitial position, the pivot pin 3| is again lifted so that the lever 29 has the position shown in Fig. 5 when the carriage reaches the left end of its travel.

The proper actuation of the contact member 63 is effected by-means of a control cam or the like mechanism. (not shown) actuated fromV the loom drive infproper correlation to the other operating devices of thev machinery. The velocity of the carriage II as it travels along the guide rails I3 and I4 is determined by the angular position or theA roller' axis. Sincev this position is at all times ccmtrolledl by the controllable positioning of the cam member or lever'29, the translational velocity and acceleration of the carriage is always subject to a definite control action.

Inorder' to impart to the carriage a desired motion, for instance one which has constant acceleration up to the moment of maximum speed at which the shuttle will ily off, the angular adjustment of the pivot shaft 9A must follow the proper law as a function of time. This is done by tilting the end at which the carriage is located when it starts its movement about the pivot axis of the other cam pivot member. The rate at which the roller pivot is turned depends of course on the operating characteristics of the lever mechanism and the appertaining hydraulic con trol devices. These conditions may be such that the desired character of motion, for instance motion of constant acceleration, cannot readily be obtained if the cam surface or slot of the cam member is of straight shape. However, Whatever the law of motion of the'tilting end of the cam lever 29 may be, the curvature` of theA cam slot may be chosen so as to cause the carriage to move with constant or other desired acceleration. This moves any restrictions on the type oi adjusting and control devices used for controlling the position of the cam lever. It thus will be clear that adjusting devices other than the hydraulic type device exemplified by the drawings can be used if desired. For instancethe cam lever may be directly actuated by control cams which form part of the loom driving ma"- chinery.

When` using a vhydraulic system as shown in Fig. 5, the application of a curved cam surface permits using a simple gear pump of constant speed and constant fluid displacement so that the actuated end of the control lever moves at substantially constant speed. Under these conditions, the shape of the cam curve or cam slot can be precisely calculated for the condition of constant output acceleration of the drive car riage or for any other prescribed law of motion. For obtaining constant acceleration and operate ing with-a lever displacement of constant speed, the cam slot has substantially the curved shape shown in Fig. 5.

As mentioned above, the cam member is pref-- erably designed so that the carriage reached maximum speed at the midpoint of its travel, and the roller pivot isk then gradually brought back to its vstarting position. The law of return motion under the action of the spring 36 or 39, in general, Will be diierent from the law of lever motion eiected by the hydraulic control system, but the curvature of the lever slot for the second half of the carriage travel can readily be designed to bring the carriage to a stop with constant deceleration or with any law of deceleration within the range of the mechanism.

After the carriage has reached the end of its shuttle driving travel, it is returned to its starting point by pivoting the slotted lever 29 about its left-end pivot 32 and, first lowering the right-hand pivot 3| in order to accelerate the shuttle and then raising the right-'end pivot 3| backto its illustrated position to decelerate the shuttle to' astop. The' time for the return motion of the carriage maybe longer than that'for forward motion by at least the time required by the shuttle to travel to the other side of the loom and back. Therefore, the return accelerations of the carriage may be considerably lower and it is not necessary to provide for constant acceleration on carriage return. This means that little consideration need'be given to the design and operation of the return control elements. By the same token, the shape of the cam slot is less important for the return stroke so that a slot curve that is designed for constant acceleration on the forward stroke of the carriage motion will still be satisfactory for the lesser requirements of the return motion.

Since the two pivot points of the control lever should preferably lie on a line parallel to the line of carriage travel, another important advantage of the curved slot becomes apparent when one considers what would happen if a straight slot were used and if the proper law of carriage motion Were attained solely by a proper shaping of the lever actuating cam or by properly varying the flow to the actuating hydraulic cylinders. For one thing, a straight control slot wouldy have to have its axis exactly in a plane passing through the axis of the drive rotor I. The slightest tilt from parallelism with this plane would result in a tilt of the fork 3 and cause a slow creep of the drive carriage to the end of its travel, at which point a sliding and abrasion of wheel 2 and rotor I would take place. Moreover, even if the slot axis were properly oriented, the unavoidable clearance between the roller and its slot, and'between the roller shaft and roller would still make it possible for fork 3 to tilt slightly and creep in one direction or the other during the intervals of time when the shuttle was not being propelled.

The difficulty of unwanted creep of the carriage is completely eliminated by making the cam surface or slot curved and by making it intersect at an angle the line parallel to the drive rotor axis. For example, When the tangent to the slot axis intersects the line in question at an acute angle in a clockwise sense at each end of the slot, the carriage position of rest is definitely determined by these points of intersection, Then, any tendency for the carriage to creep oif the intersection points causes the slot to turn the crank arm i4 of fork 3 in such a direction as to return the carriage to the points of intersection in question. The carriage may then be said to be self-regulated as to the stability of its stopping position at each end of its stroke.

Although the frictional servo-rotor specifically described in the foregoing and shown in the drawings is designed as a shuttle drive for Weaving looms, it is apparent that the invention can likewise be embodied in mechanisms for other purposes, such as the propulsion or control of torpedoes, aircraft, gun control systems, and, in general, in servo-mechanisms for which an aperiodic or non-oscillatory response is desirable.

It should also be understood that while I have illustrated and specifically described a mechanism whose driving rotor is cylindrical, the rotor'may be given conical shape or generally the shape of a body of revolution. It will be obvious to those skilled in the art upon study of this disclosure that modifications, embodiments, and applications of the invention other than those specifically mentioned are possible, in accordance with the gist and principles of my invention, and withbut departure from the essential features of the 8 invention'set forth in the claims annexed here- I claim as my invention: l

1. A device for deriving translational motion from a source of rotary power, comprising a rotor shaped as a body of revolution with a substantially straight generatrix and revolvable about its 4geometric axis, a, structure movable along said rotor, a pivot journalled on said structure, a roller revolvably mounted on said pivot about a roller axis extending at a right angle to that of said pivot, said roller being in frictional engagement with said rotor, a crank member on said pivot for turning the latter, a cam member having a slot engaged by said crank member and extending along the path of travel of said structure for turning said pivot during said travel.

2. A device for deriving translational motion from a source of rotary power, comprising a rotor, a structure movable along said rotor, a pivot shaft revolvably mounted on said structure, a roller in frictional engagement with said rotor and revolvably mounted on said pivot shaft so that the axis of roller revolution extends at a right angle to the axis of said pivot shaft, a crank member attached to said pivot shaft for turning said shaft in order to vary the angular position of said axis of revolution relative to the direction of the generatrix of said rotor at the point of engagement with said roller, a cam member extending along the path of travel of said structure and engaging said crank member during the travel of said structure for turning said pivot, and control means connected with said cam member for moving it to cause saidr crank member to turn said pivot shaft.

3. A device for deriving translational motion from a source of rotary power, comprising a rotor, a structure movable along said rotor, a pivot shaft revolvably mounted on said structure, a roller in frictional engagement with said rotor and revolvably mounted on said pivot shaft so that the axis of roller revolution extends at a right angle to the axis of said pivot shaft, a crank member attached to said pivot shaft for turning said Vshaft in order to vary the angular position of saidV axis of revolution relative to the direction of the generatrixV of said rotor at the point of engagement with said roller, a movable cam member extending along the path of travel of said structure and engaging said crank member during the travel of said structure for turning said pivot, and control means connected With said cam member for moving it to cause said crank member to turn said pivot shaft. V

r4. A device for deriving translational motion from a source of rotary power, comprising a rotor Shaped as an elongated -body of revolution with a substantially straight generatrixl and being revolvable about its geometric axis, a structure movable along said drive'member, a pivot member mounted on said structure and being revolvable relative thereto, a friction roller revolvably mounted on said pivot member and in frictional engagement with the peripheral surface of said rotor, said pivot member having a crank member for turning said pivot member to control the angular position of the axis of revolution of said roller relative to the direction 'of the generatrix of said rotor member at the point of engagement with said roller so that. during revolution of said rotor, saidstructure is driven along said rotor when said roller axis is Placed at an .angle to said direction, a, .lever exiaglivasec '9 tending-along saidrotor and' havinga slot engaginglsaid cran-k membenpivot means engaging said-'lever'at one end thereof, and control means connected to Asaid lever for moving it about said Vpivot means in order to `control said Vlever to turn said pivot member.

5. A device for imparting controlled translav tional motion from a'source of rotary power, ncomprising a stationary supporting frame, a ro- -tor shaped as a body of revolution with a substantially straight generatrix and being revolvable about its geometrical axis relative to said frame,- a structure guided on said frame for motion jalong said rotor,v a pivot member -revolvably mounted on said structure, africticn` roller revolvably mounted on said pivot member and in frictional engagement with said rotor, said pivot member having a crank for turning said pivot lmember in' order to control the angular'position of-the'axis :of revolution of --said roller relative Yto the ldirection of the generatrix of said rotor so that, during revolution of said rotor, said structure is caused by said roller to travel along said rotor when said roller axis is placed at an angle to said direction, a lever having a cam surface extending along said rotor and slidably engaged by said crank for progessively turning said pivot member as said structure travels along said rotor, two pivoting devices linked to said lever at pivot points near the respective ends of said cam surface, and control means connected to said pivoting devices for causing either device to move said lever about the pivot point of said other device.

6. A device for imparting controlled translational motion from a source of rotary power, comprising a stationary supporting frame, an elongated rotor revolvable relative to said frame, a structure guided on said frame for motion along said rotor, a pivot member mounted on said support and being revolvable relative thereto, a friction roller mounted on said pivot member for revolution about an axis at a right angle to that of said pivot member, said roller being in frictional engagement with said rotor, said pivot member having a crank for turning the axis of revolution of said roller at an angle to the direction of the generatrix of said rotor in order to cause said structure to move along said rotor, a control lever having a cam surface extending along said rotor and engageable by said crank in all travelling positions of said structure, said lever having two pivot means disposed near the respective ends of said cam surface, two actuating devices linked to said respective pivot means and having each a spring for normally holding said lever in a given position, and control means connected with said devices for causing either device to move the appertaining pivot means in opposition to the appertaining spring about the axis of the other pivot means.

7. A shuttle drive, comprising an elongated cylindric rotor revolvable about its cylinder axis, a wheeled carriage movable along said rotor in parallel to said axis and having shuttle engaging means for imparting motion to the shuttle to be driven, a pivot member mounted on said carriage so as to be revolvable relative thereto, a friction roller revolvably mounted on said pivot member and in frictional engagement with the cylindric surface of said rotor, a crank arm forming part of said pivot member for turning it relative to said structure in order to control the angular position of the roller relative to said cylinder axis so that,`duringrevolution of said rotor, said struc- `ture remains fat rest `when said roller axis is in `tions, control meansfor controlling said adjust- Ning means to movesaid cam member for starting Land stopping-said carriage,

Af8. A `shuttle drive, -com'prising an elongated cylindric rotor/revolvable about its cylinder axis,

afwheeled carriage movable along said rotor in parallel to said axis and having shuttle engaging means-for imparting motion to the shuttle to be driven, a pivot-member mounted on said carriage so as to be revolvable relative thereto, a friction roller'-revolvablyy mounted on said pivot member an'dinI frictionalengagement with the cylindric surface of said rotor, a crank arm forming part of said pivot member for turning it relative to .said structure in order to control the angular position of the roller relative to said cylinder axis so that, during revolution of said rotor, said structure remains at rest when said roller axis is in parallel to said cylinder axis and is caused to move along said drive member when said roller axis is placed at an angle to said cylinder axis, a movable cam member having a cam surface extending along said rotor and engaging said crank member in all travelling positions of said carriage, said cam member being movable from an intermediate position to two limit positions and having two pivot means spaced from each other, two adjusting devices engaging said respective pivot means, spring means for biasing said adjusting devices to normally hold said cam member in said intermediate position, and control means connected with said devices for alternately controlling them' so that either device, when operative, moves said cam member about the pivot means engaged by the other device.

9. A shuttle drive, comprising an elongated cylindric rotor revolvable about its cylinder axis, a wheeled carriage movable along said rotor in parallel to said axis and having shuttle engaging means for imparting motion to the shuttle to be driven, a pivot member mounted on said carriage so as to be revolvable relative thereto, a friction roiler revolvably mounted on said pivot member and in frictional engagement with the cylindric surface of said rotor, a crank arm forming part of said pivot member for turning it relative to said structure in order to control the angular position of the roller relative to said cylinder axis so that, during revolution of said rotor, said structure remains at rest when said roller axis is in parallel to said cylinder axis and is caused to move along said drive member when said roller axis is placed at an angle to said cylinder axis, a movable cam member having a cam surface extending along said rotor and engaging said crank member in all travelling positions of said carriage, said cam surface being curved in accordance with a desired control performance, and control means connected with said cam member for moving it in order to turn said pivot member in a position to start movement of said carriage whereupon said pivot member during said movement is gradually returned to carriage-stopping position in accordance with the performance determined by the curvature of said surface.

10. A shuttle drive, comprising an elongated cylindric rotor revolvable about its cylinder axis, a wheeled carriage movable along said rotor in parallel to said axis and having shuttle engaging means for imparting motion to the shuttle to be driven, a pivot member mounted on said carriage so as to be revolvable relative thereto, a friction roller revolvably mounted on said pivot member and in frictional engagement with the cylindric surface of said rotor, a crank arm forming part of said pivot member for turning it relative to said structure in order to control the angular position of the roller relative to said cylinder axis so that, during revolution of said rotor, said structure remains at rest when said roller axis is in parallel to said cylinder axis and is caused to move along said drive member when said roller axis is placed at an angle to said cylinder axis, an elongated lever having a slot extending along said rotor and engaged by said crank, said lever having two pivot means near the respective ends of said slot, two hydraulic adjusting devices engaging said respective pivot means and having spring means for biasing said pivot means toward given positions respectively, and Valve means for alternately actuating said adjusting means to move the respective pivot means away from' said normal position in order to turn said pivot member in a position to start movement of said carriage whereupon said pivot member during said movement is gradually returned to carriage-stopping position as said crank moves along said slot.

STANLEY J. MIKINA.

CTEED The following referen'ces are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,215,678 Weathers Sept. 24, 1940 20 2,382,105 Sarver Aug. 14, 1945 2,428,807 Mikina Oct. 14, 1947 

